A Japanese Patent Application laid open No. JP2011-165931A has disclosed a circuit module that provides the first printed circuit board (PCB) to mount electrical components operable in a radio frequency (RF) range and the second PCB disposed against the first PCB. The second PCB provides hollows into which the electrical components in the first PCB are set, where the hollows are surrounded by walls for forming via holes and conductive patterns formed on a top surface and/or inner surfaces thereof. Conductive patterns in the top surfaces of the first and second PCBs are attached and electrically connected to each other. The hollows in the second PCB receive the electrical components and electrically isolate to each other.
Another Japanese Patent application laid open No. JP2014-132651A has disclosed a package for an electrical device operable in microwave frequencies and higher power. The package disclosed therein provides a frame made of ceramics and a metal base made of at least one of copper (Cu), a composite containing copper and Diamond, and a composite containing aluminum (Al) and Diamond. The frame, to which a lead terminal is brazed, is hermetically attached to the meal base with metal powder type of low temperature sintering. A package for an RF device may be generally formed by a metal base, a ceramic frame with a lead terminal, and a ceramic lid. The ceramic frame is brazed to the metal base, and the lead terminal is brazed to the ceramic frame. Furthermore, the lid is brazed to the ceramic frame to enclose a semiconductor chip and circuit components each mounted on the metal base air-tightly. An RF device for a low noise and a small signal application sometimes provides a base made of ceramics instead of the metal base.
However, such a package for an RF device formed by the metal base, the ceramic frame, and the ceramic lid generally shows lesser cost merit. An RF device whose frame, sometimes accompanying with a lid, is substituted into one made of resin, such as glass epoxy, may show remarkable cost merit; but leaves subject in an assembly process thereof. That is, a resin made package may reduce material cost but leave assembly cost thereof in relatively high.